Capturing the elusive molecules to further drug treatments

An advancement in analysing phosphorylated proteins - which govern how living organisms work - has been made by a Malmö University researcher at the Biofilms Research Center for Biointerfaces.

Such analysis is crucial to facilitate the development of new diagnostic and therapeutic tools, and now Celina Wierzbicka is set to defend her research with her thesis, ‘New Fractionation Tools Targeting Elusive Posttranslational Modifications’.

“The human body is a complex machine executing an enormous number of biochemical reactions every second. Crucial element ensuring the integrity of the whole organism is the communication between individual cells. One of the methods used by living organisms for this purpose is reversible phosphorylation of proteins.

A better understanding for better treatments

“This type of protein modification affects almost all biological processes in living organisms – including humans. For example, phosphorylated proteins are responsible for the regulation of cell metabolism. The abnormal phosphorylation of proteins may result in the development of some diseases, for example cancer.

“If we study the phosphorylated proteins and understand their role in disease development and progression, it is possible to identify drug targets and develop new drugs” she explained.

While this is not a new field of study, Celina believes there are many things that could be improved. The phosphoproteins are most commonly analysed by mass spectrometry. However, in a typical biological sample phosphoproteins are low in abundance and might consist of only a very small fraction of all the proteins which makes them hard to analyse. In order to see them, they need to be enriched and it is this enrichment step which is the focus of the research.

New and improved technique

“We have developed materials and methods that can be used to selectively enrich phosphopeptides -small fragments of phosphoproteins - from biological samples.”

This was done using the molecular imprinting technology, which relies on the formation of rigid polymeric material in presence of template molecule.

“It is then possible to remove the molecule, which has left a print in the polymer. Cavities formed in this way are then able to recognise the same or very similar molecule and bind to it. All other molecules will not fit in the cavity and thus can be removed from the sample. In this way, phosphopeptides can be effectively extracted even from complex biological samples.”

More cost effective and stable

The method has advantages over the commonly used antibodies which are both very expensive and require special storage and handling conditions. The polymers instead are cheap to produce and stable in harsh conditions. Additionally, the selectivity of the polymer can be programmed to target a specific phosphorylation site, thus enabling access to low abundant and labile modifications such as phosphorylation on tyrosine or histidine residues.